A piezoelectric actuator, which uses an inverse piezoelectric effect or an electrostrictive effect as a driven force, generally has advantages of low actuation voltage and large displacement. These advantages of the piezoelectric actuator can be attractive for microelectromechanical system (MEMS) devices, such as MEMS switches and capacitors.
However, a conventional cantilever beam actuator, which has a long thin beam structure including a piezoelectric film interposed between upper and lower electrodes, usually curls upward or downward by slight residual stress of multiple layers of thin films. However, this may result in disparity of the driving voltage to the design value, and may even lead to failure of the device.